After DNA extraction, next-generation sequencing of 16S rRNA gene fragments was used to determine bacterial phyllosphere community structure on individual leaves, focusing on comparisons on different leaves of the same tree and on leaves of trees at different distances. The development of both approaches greatly increased our ability to describe microbial diversity and led to the realization that uncultivated. Interactions within the phyllosphere can have many outcomes, including host plant evolutionary fitness, crop safety for human consumption, and agricultural crop productivity (Whipps et al. 2008).
Various environmental factors can influence the composition of the microbial community on leaf surfaces, and there is evidence to suggest that plant genotype also plays a role in determining microbial communities in the phyllosphere (Whipps et al. 2008). A number of studies have investigated the diversity of bacterial communities on the surface of different leaves, but relatively few have investigated their spatial variability or differences in the phyllosphere community structure between individuals of the same plant species. The purpose of the study was not only to describe the composition of the magnolia phyllosphere community, but to.
The V4 region of the bacterial 16S rRNA gene was amplified and sequenced using a barcoded Illumina next-generation sequencing approach (Kozich et al. 2013). After clustering the 16S rRNA gene sequences based on a 97% similarity criterion, the total number of detected OTUs was 10,005. Eleven of the twenty most abundant OTUs classified as Alphaproteobacteria; eight of them identifying within the order Rhizobiales, including the three most abundant (OTUs and 00013).
Other bacterial phyla each accounted for less than 1% of the total number of sequences recovered and included Firmicutes, Chlorobi, Nitrospirae, Gemmatimonadetes and Crenarchaeota. Bacteroidetes, comprising over 11% of the total number of sequences, was the second most abundant phyla, but ranged from 2% of sequences recovered from Tree043b to almost 30% from Tree049b. Overall, both of these phyla accounted for nearly 10% of the total amount of recovered sequences.
NMDS
The purpose of this project was to investigate bacterial communities in Southern Magnolia in order to gain insight into the spatial patterns of the phyllosphere by determining how distance between trees affects changes in bacterial community composition. In addition to determining the similarity in the bacterial phyllosphere community of different trees, the degree of similarity between leaves from the same tree was also examined. Comparing the community on two leaves taken from the same tree, 14 of the 20 trees sampled had similar bacteria on the surface of each leaf.
Sampling a larger number of leaves from an individual tree, perhaps from different locations (different heights, internal versus external branches) would provide additional information about the level of phyllosphere variation within a single tree. Although most trees showed similar communities on their two leaves, as indicated by the close coordinates of the NMDS consecration, there were some exceptions. Although the two leaves per tree were collected from the same location on the tree, sampling did not take into account the potential age of the leaf, nor its health (whether it was beginning to show signs of decay), nor leaf size (leaf surface). area).
Future studies of this nature should more carefully characterize individual leaf characteristics, as well as those of the sample tree, to more accurately assess patterns in the phyllosphere. In contrast, plant species, as opposed to location, appear to drive the composition of the pine phyllosphere community, as all samples yielded the same bacterial community regardless of the location of the sampling site (Rastogi et al 2013). Correlations between plant species and bacterial community composition suggest that plant genetic factors play a major role in determining the type of bacteria found on the plant surface.
Several chemical and physical factors limit the growth of the phyllosphere, meaning that there must be selection for bacterial phenotypes that can overcome these limitations, such as phenotypes that can modify the microhabitat to increase nutrient availability (Lindow and Brandl 2003 ). Specific taxa that were high in abundance based on the number of sequences recovered included Methylobacterium, Sphingomonas, and Pseudomonas, all of which are commonly found on the plant surface (Delmotte et al. 2009). Furthermore, the relative proportion of UV-tolerant bacterial strains increases in parts of the day when UV exposure was highest (Lindow and Brandl 2003).
Many of the most abundant OTUs classified as members of the order Rhizobiales, a group of. Overall, the most abundant bacteria found on the Magnolia leaf surface were not uncommon or unusual and likely represent a typical phyllosphere community. In terms of spatial variability, leaves from the same tree tended to have similar bacterial communities on them, although there was occasional variation resulting from leaf-to-leaf variation in age, health and leaf surface area.
Annual and seasonal changes in the phyllosphere bacterial community associated with Southern Magnolia (Magnolia grandiflora) leaves. Development of a dual-index sequencing strategy and a curation pipeline for analyzing amplicon sequencing data on the MiSeq Illumina sequencing platform.
